# import sys

# list = [1,2,3,4]
# lt = iter(list)

# for x in lt:
#       print(x,end=" ")

# while True:
#       try:
#             print(next(lt))
#       except StopIteration:
#             sys.exit()

class MyNumbers:
      def __iter__(self):
            self.a = 1
            return self
      
      def __next__(self):
            if self.a <=20:
                  x = self.a
                  self.a += 1
                  return x
            else:
                  raise StopIteration
      

myclass = MyNumbers()
myiter = iter(myclass)

for x in myiter:
      print(x)